A standard feature of many modern vehicles, including private and industrial vehicles, is the ability for one or more side mirrors of the vehicle to fold in and out from the side of the vehicle. The driver is able to manually control the position of the mirror such that, when, for example the car is parked, the driver will switch the mirror into a folded position to lie adjacent to the external surface of the car. When the car is about to be driven, the driver can select the fold out position and the mirror will fold out from the side of the car and assume an extended position in the normal fashion, to allow the mirror to be used while driving.
A common factor to be taken into consideration when designing electronic circuits, particularly when associated with mechanical actuators, is the production of heat. In the case of fold out mirrors, small electric motors drive the movement of the mirror and in doing so, generate heat. Traditionally, because the power fold function is used infrequently, the generation of heat is not a major problem. However, there may be instances where the power fold function is used frivolously, for example a child playing with the power fold switch and repeatedly folding the mirror in and out. This may result in overheating of the motor and surrounding electronic components and may damage the components of the mirror system.
Traditional ways of dealing with overheating include the provision of heat sinks, which provide a large surface area in contact with the surrounding air to radiate heat therefrom, and in the case of circuit boards, larger PCBs can be used to provide the larger heat radiating area.
Other methods of compensating for the generation of heat include using heavier duty components which are more expensive. This is undesirable in a product which is mass manufactured as the overall increase in cost can be dramatic. Similarly, in devices such as power fold control circuits, space is often at a premium and it is necessary to keep component and board sizes as small as possible.
It is an object of the present invention to provide an alternative means of addressing the problem of potentially damaging heat.